Bluetooth: ISO: Add BIG callbacks

Add callbacks that is called for the entire BIG.
The BIG state is from an HCI perspective a single state change
that we previously only propagated as a state change for each
channel.

However it may be simpler for applications and higher layers
to use BIG changes to trigger their behavior.

Signed-off-by: Emil Gydesen <emil.gydesen@nordicsemi.no>

include/zephyr/bluetooth/iso.h

@@ -34,6 +34,7 @@
 #include <zephyr/sys/atomic.h>
 #include <zephyr/sys/slist.h>
 #include <zephyr/sys/util_macro.h>
+#include <zephyr/sys/slist.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -1102,6 +1103,42 @@ int bt_iso_chan_get_info(const struct bt_iso_chan *chan, struct bt_iso_info *inf
  */
 int bt_iso_chan_get_tx_sync(const struct bt_iso_chan *chan, struct bt_iso_tx_info *info);
 
+/**
+ * @brief Struct to hold the Broadcast Isochronous Group callbacks
+ *
+ * These can be registered for usage with bt_iso_big_register_cb().
+ */
+struct bt_iso_big_cb {
+	/**
+	 * @brief The BIG has started and all of the streams are ready for data
+	 *
+	 * @param big The started BIG
+	 */
+	void (*started)(struct bt_iso_big *big);
+
+	/**
+	 * @brief The BIG has stopped and none of the streams are ready for data
+	 *
+	 * @param big The stopped BIG
+	 * @param reason The reason why the BIG stopped (see the BT_HCI_ERR_* values)
+	 */
+	void (*stopped)(struct bt_iso_big *big, uint8_t reason);
+
+	/** @internal Internally used field for list handling */
+	sys_snode_t _node;
+};
+
+/**
+ * @brief Registers callbacks for Broadcast Sources
+ *
+ * @param cb Pointer to the callback structure.
+ *
+ * @retval 0 on success
+ * @retval -EINVAL if @p cb is NULL
+ * @retval -EEXIST if @p cb is already registered
+ */
+int bt_iso_big_register_cb(struct bt_iso_big_cb *cb);
+
 /**
  * @brief Creates a BIG as a broadcaster
  *

subsys/bluetooth/host/iso.c

@@ -2525,6 +2525,8 @@ int bt_iso_chan_connect(const struct bt_iso_connect_param *param, size_t count)
 #endif /* CONFIG_BT_ISO_UNICAST */
 
 #if defined(CONFIG_BT_ISO_BROADCAST)
+static sys_slist_t iso_big_cbs = SYS_SLIST_STATIC_INIT(&iso_big_cbs);
+
 static struct bt_iso_big *lookup_big_by_handle(uint8_t big_handle)
 {
 	return &bigs[big_handle];
@@ -2587,6 +2589,16 @@ static void big_disconnect(struct bt_iso_big *big, uint8_t reason)
 
 		bt_iso_chan_disconnected(bis, reason);
 	}
+
+	if (!sys_slist_is_empty(&iso_big_cbs)) {
+		struct bt_iso_big_cb *listener;
+
+		SYS_SLIST_FOR_EACH_CONTAINER(&iso_big_cbs, listener, _node) {
+			if (listener->stopped != NULL) {
+				listener->stopped(big, reason);
+			}
+		}
+	}
 }
 
 static int big_init_bis(struct bt_iso_big *big, struct bt_iso_chan **bis_channels, uint8_t num_bis,
@@ -2617,6 +2629,25 @@ static int big_init_bis(struct bt_iso_big *big, struct bt_iso_chan **bis_channel
 	return 0;
 }
 
+int bt_iso_big_register_cb(struct bt_iso_big_cb *cb)
+{
+	CHECKIF(cb == NULL) {
+		LOG_DBG("cb is NULL");
+
+		return -EINVAL;
+	}
+
+	if (sys_slist_find(&iso_big_cbs, &cb->_node, NULL)) {
+		LOG_DBG("cb %p is already registered", cb);
+
+		return -EEXIST;
+	}
+
+	sys_slist_append(&iso_big_cbs, &cb->_node);
+
+	return 0;
+}
+
 #if defined(CONFIG_BT_ISO_BROADCASTER)
 static int hci_le_create_big(struct bt_le_ext_adv *padv, struct bt_iso_big *big,
 			     struct bt_iso_big_create_param *param)
@@ -3006,6 +3037,16 @@ void hci_le_big_complete(struct net_buf *buf)
 		store_bis_broadcaster_info(evt, &iso_conn->iso.info);
 		bt_conn_set_state(iso_conn, BT_CONN_CONNECTED);
 	}
+
+	if (!sys_slist_is_empty(&iso_big_cbs)) {
+		struct bt_iso_big_cb *listener;
+
+		SYS_SLIST_FOR_EACH_CONTAINER(&iso_big_cbs, listener, _node) {
+			if (listener->started != NULL) {
+				listener->started(big);
+			}
+		}
+	}
 }
 
 void hci_le_big_terminate(struct net_buf *buf)
@@ -3186,6 +3227,16 @@ void hci_le_big_sync_established(struct net_buf *buf)
 		store_bis_sync_receiver_info(evt, &iso_conn->iso.info);
 		bt_conn_set_state(iso_conn, BT_CONN_CONNECTED);
 	}
+
+	if (!sys_slist_is_empty(&iso_big_cbs)) {
+		struct bt_iso_big_cb *listener;
+
+		SYS_SLIST_FOR_EACH_CONTAINER(&iso_big_cbs, listener, _node) {
+			if (listener->started != NULL) {
+				listener->started(big);
+			}
+		}
+	}
 }
 
 void hci_le_big_sync_lost(struct net_buf *buf)